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1.
Dokl Biochem Biophys ; 486(1): 206-208, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31367822

RESUMO

The aim of this work was to study the fine structure of bacterial films grown on the inner tube surface of a flow reactor. Using the scanning electron microscopy (SEM) approaches, the detailed biofilm relief was visualized. The action of electrochemically reduced water (ERW) on the biofilm ultrastructure generated by the plankton form of E. coli and/or lacto bacteria was investigated. The treatment with an ERW solution destroyed the biofilm organic polymer matrix and bacterial cells embedded in the matrix.


Assuntos
Biofilmes/efeitos dos fármacos , Água/química , Água/farmacologia , Biofilmes/crescimento & desenvolvimento , Eletroquímica , Escherichia coli/efeitos dos fármacos , Escherichia coli/fisiologia
2.
Yakugaku Zasshi ; 139(7): 975-986, 2019.
Artigo em Japonês | MEDLINE | ID: mdl-31257255

RESUMO

We have found that the spiro form of aminobenzopyranoxanthene (ABPX) exhibits dual solvatochromic and nanoaggregate fluorescence in organic solvents by spectrophotometric and theoretical analyses. The dual fluorescence properties of ABPX were adjustable in response to water content, and served as a new detection principal for naked-eye visualization (above 0.5 wt%) and quantification (0.010-0.125 wt%) of water in tetrahydrofuran. In investigating the optical properties of a dicationic form of ABPX, ABPX containing linear n-alkyl chains at amino groups were then synthesized. These ABPX exhibited fluorescence emission in the far-red and NIR wavelength regions, and we noted an increased fluorescence quantum efficiency with increasing n-alkyl chain length. To further improve the fluorescence quantum yields, we have designed and synthesized ABPX with different nitrogen-containing fused rings. It was kinetically demonstrated that the structurally rigid conjugation of the xanthene moiety is an effective molecular design for the drastic enhancement of fluorescence emission efficiency.


Assuntos
Química Orgânica , Eletroquímica , Xantenos/química , Furanos , Cinética , Nanopartículas , Rodaminas , Solventes , Espectrometria de Fluorescência , Água , Xantenos/síntese química
3.
Int J Nanomedicine ; 14: 4833-4847, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31308661

RESUMO

Background: The use of functionalized graphene oxide (fGO) has led to a new trend in the sensor field, owing to its high sensitivity with regards to sensing characteristics and easy synthesis procedures. Methods: In this study, we developed an ultra-sensitive carboxyl-graphene oxide (carboxyl-GO)-based surface plasmon resonance (SPR) aptasensor using peptides to detect human chorionic gonadotropin (hCG) in clinical serum samples. The carboxyl-GO based SPR aptasensor provided high affinity and stronger binding of peptides, which are great importance to allow for a non-immunological label-free mechanism. Also, it allows the detection of low concentrations of hCG, which are in turn considered to be important clinical parameters to diagnose ectopic pregnancies and paraneoplastic syndromes. Results: The high selectivity of the carboxyl-GO-based SPR aptasensor for hCG recombinant protein was verified by the addition of the interfering proteins bovine serum albumin (BSA) and human serum albumin (HSA), which did not affect the sensitivity of the sensor. The carboxyl-GO-based chip can enhance the assay efficacy of interactions between peptides and had a high affinity binding for a ka of 17×106 M-1S-1. The limit of detection for hCG in clinical serum samples was 1.15 pg/mL. Conclusion: The results of this study demonstrated that the carboxyl-GO-based SPR aptasensor had excellent sensitivity, affinity and selectivity, and thus the potential to be used as disease-related biomarker assay to allow for an early diagnosis, and possibly a new area in the field of biochemical sensing technology.


Assuntos
Técnicas Biossensoriais/instrumentação , Gonadotropina Coriônica/sangue , Grafite/química , Ressonância de Plasmônio de Superfície/instrumentação , Animais , Bovinos , Eletroquímica , Humanos , Peptídeos/química , Espectroscopia Fotoeletrônica , Soroalbumina Bovina/química
4.
Nat Commun ; 10(1): 2440, 2019 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-31164649

RESUMO

Soil contamination by heavy metals constitutes an important environmental problem, whereas field applicability of existing remediation technologies has encountered numerous obstacles, such as long operation time, high chemical cost, large energy consumption, secondary pollution, and soil degradation. Here we report the design and demonstration of a remediation method based on a concept of asymmetrical alternating current electrochemistry that achieves high degrees of contaminant removal for different heavy metals (copper, lead, cadmium) at different initial concentrations (from 100 to 10,000 ppm), all reaching corresponding regulation levels for residential scenario after rational treatment time (from 30 min to 6 h). No excessive nutrient loss in treated soil is observed and no secondary toxic product is produced. Long-term experiment and plant assay show the high sustainability of the method and its feasibility for agricultural use.


Assuntos
Eletroquímica/métodos , Recuperação e Remediação Ambiental/métodos , Metais Pesados , Poluentes do Solo , Solo/química , Agricultura , Cádmio , Cobre , Estudos de Viabilidade , Chumbo
5.
World J Microbiol Biotechnol ; 35(5): 73, 2019 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-31037431

RESUMO

Metal corrosion is a major global concern in many economic sectors. The degradation of metal surfaces is responsible for losses in values that account for about 3% of gross domestic product (GDP) only in the US. Parts of all corrosion processes described in different environments are present mainly in marine environments. The marine environment is characterized as favoring the corrosion processes of several metallic alloys, damaging structures used in the construction of ships, ports, oil pipelines, and others. Despite chemical corrosion being the most frequently described in these environments, studies show the participation of microorganisms in direct corrosion processes or in the acceleration/influence of the corrosive action, through the formation of complex biofilms. These structures create favorable conditions for microorganisms to degrade metal surfaces, causing damage known as pitting and crevices. Currently, diverse technicians are employed in biocorrosion research, e.g. electronic microscopy, and DNA sequencing. These techniques have clarified the dynamic process of the formation of biofilm structures, allowing understanding of the succession of different species during the evolution of the structure. Improving the understanding of how this interaction between biofilm and metallic surface occurs will enable better evaluation of strategies to avoid or decelerate the degradation of metallic structures in marine environments.


Assuntos
Biofilmes/crescimento & desenvolvimento , Água do Mar/microbiologia , Aço/química , Ligas/química , Bactérias/metabolismo , Aderência Bacteriana/fisiologia , Fenômenos Fisiológicos Bacterianos , Corrosão , Eletroquímica , Metais/química , Propriedades de Superfície
6.
Phys Chem Chem Phys ; 21(20): 10761-10772, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-31086930

RESUMO

This study describes and evaluates a dynamic computational model for a two chamber microbial electrosynthesis (MES) system. The analysis is based on redox mediators and a two population model, describing bioelectrochemical kinetics at both anode and cathode. Mass transfer rates of the substrate and bacteria in the two chambers are combined with the kinetics and Ohm's law to derive an expression for the cell current density. The effect of operational parameters such as initial substrate concentration at the anode and cathode and the operation cycle time on MES performance is evaluated in terms of product formation rate, substrate consumption and coulombic efficiency (CE). For a fixed operation cycle time of 3 or 4 days, the anode and cathode initial substrate concentrations show linear relationship with product formation rate; however MES operation with a 2 day cycle time shows a more complex behaviour, with acetic acid production rates reaching a plateau and even a slight decrease at higher concentrations of the two substrates. It is also shown that there is a trade-off between product formation rate and substrate consumption and CE. MES performance for operation with cycle time being controlled by substrate consumption is also described. Results from the analysis demonstrate the interdependence of the system parameters and highlight the importance of multi-objective system optimization based on targeted end-use.


Assuntos
Bactérias/metabolismo , Fontes de Energia Bioelétrica , Eletroquímica/instrumentação , Reatores Biológicos , Eletrodos
7.
Ultrason Sonochem ; 56: 134-142, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31101247

RESUMO

Herein, we have reported a simple sonochemical synthesis of multi-layer graphene covered tungsten trioxide nanoballs (WO3 NBs) and the nanocomposite was characterized by FESEM, HRTEM, XRD, XPS, CV and EIS. Furthermore, progesterone (PGT) is a preferred marker for various biological problems like pregnancy problem, mood swings, anxiety, depression, nervousness and body pain. Therefore, its selective and sensitive determination in various biological fluids is beneficial for the evaluation of malformation problems. We describe the fabrication of an amperometric and non-enzymatic biosensor based on WO3 NBs@GR nanocomposite modified electrode for nanomolar detection of PGT. The results showed that the nanocomposite modified electrode exhibit well-defined electro-oxidation peak compared to bare and control electrodes, demonstrating the superior electrocatalytic ability and performances. The fabricated modified sensor was facilitates the analysis of PGT in the concentration ranges of 0.025-1792.5 µM with a low detection limit of 4.28 nM. Further, the as-prepared WO3 NBs@GR electrode has been applied to determination of PGT in human blood samples with outstanding recovery results and more importantly, the facile and environment-friendly sonochemical construction strategy extended here, may be open a cost-effective way for setting up the nanocomposites based (bio) sensing platform.


Assuntos
Eletroquímica/instrumentação , Grafite/química , Limite de Detecção , Óxidos/química , Tungstênio/química , Ondas Ultrassônicas , Catálise , Técnicas de Química Sintética , Eletrodos , Oxirredução , Propriedades de Superfície , Temperatura Ambiente
8.
Ultrason Sonochem ; 56: 254-263, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31101261

RESUMO

A novel and cost-effective synthesis of biopolymer-based organic and inorganic composite materials have received substantial attention in a broad range application including electroanalysis of small molecules. In this perspective, we report the synthesis of gum guar (guar) biopolymer stabilized cupric oxide decorated on exfoliated graphite (GR-guar/CuO) composite. Different physicochemical characterization methods were used to confirm the successful exfoliation of graphite and formation of the GR-guar/CuO composite. A simple sonochemical method has been used for the preparation of guar stabilized exfoliated graphite (GR-guar). The flower-like CuO on GR-guar and guar stabilized CuO (CuO-guar) composites were synthesized using a hydrothermal method. Cyclic voltammetric studies revealed that the GR-guar/CuO composite modified screen-printed carbon electrode (SPCE) had enhanced electro-reduction ability towards H2O2 than GR-guar and pristine graphite/CuO-guar modified SPCEs. Under optimized experimental conditions, the GR-guar/CuO composite modified electrode detects H2O2 in the response ranges from 0.02 to 1296.6 µM. The sensor shows a lower detection limit of 5.8 nM with high sensitivity. The as-prepared GR-guar/CuO composite sensor is highly reproducible and had excellent selectivity and practicality towards the detection of H2O2. Consequently, the fabricated sensor can be used for the accurate detection of H2O2 in real samples.


Assuntos
Soluções para Lentes de Contato/química , Cobre/química , Galactanos/síntese química , Grafite/química , Peróxido de Hidrogênio/análise , Mananas/síntese química , Leite/química , Gomas Vegetais/síntese química , Ondas Ultrassônicas , Animais , Catálise , Técnicas de Química Sintética , Eletroquímica , Modelos Moleculares , Conformação Molecular
9.
Ultrason Sonochem ; 56: 318-326, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31101269

RESUMO

A simple and facile ultrasound based sonochemical method to incorporate Perovskite-type barium titanate (BaTiO3) nanoparticles inside the layered and reduced graphene oxide sheets (rGOs) is reported. BaTiO3@rGOs nanocomposite was characterized by FESEM, HRTEM, EDX, mapping, XRD, XPS and EIS. The results show that the decoration and also incorporation of BaTiO3 nanoparticles in the multi-layered and ultrasound reduced graphene oxide matrix. Non-enzymatic and differential pulse voltammetric sensor of ractopamine (food toxic) based on the BaTiO3@rGOs nanocomposite modified screen printed carbon electrode is developed. Compared with the original BaTiO3/SPCE and rGOs/SPCE, the BaTiO3@rGOs/SPCE displays excellent current response towards ractopamine and gives linearity in the range of 0.01-527.19 µM ractopamine in neutral phosphate buffer (pH 7.0). The BaTiO3@rGOs nanocomposite modified sensor also exhibits valuable ability of anti-interference to electroactive analytes. Furthermore, the as-prepared BaTiO3 NPs@rGOs/SPCE has been applied to the determination of ractopamine in pork and chicken samples.


Assuntos
Compostos de Cálcio/química , Grafite/química , Carne/análise , Nanopartículas/química , Óxidos/química , Fenetilaminas/análise , Titânio/química , Ondas Ultrassônicas , Técnicas de Química Sintética , Eletroquímica , Eletrodos , Análise de Alimentos , Contaminação de Alimentos/análise , Modelos Moleculares , Conformação Molecular , Oxirredução , Propriedades de Superfície , Fatores de Tempo
10.
Ultrason Sonochem ; 56: 378-385, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31101276

RESUMO

Herein, novel manganese sulfide nanoparticles (MnS NPs) decorated reduced graphene oxide (rGOS) nanocomposite have been designed through a facile ultrasound-assisted method and followed by a sonication process. After then, as-synthesized α-MnS@rGOS was characterized by HRTEM, FESEM, XPS, XRD and EIS. Furthermore, the α-MnS@rGOS nanocomposite modified SPCE (screen-printed carbon electrode) shows excellent electrochemical sensing performance towards Parkinson's disease biomarker of dopamine (DA). Moreover, the fabricated sensor showed a wide linear range for dopamine between 0.02 and 438.6 µM and nanomolar detection limit (3.5 nM). In addition, the α-MnS@rGOS modified SPCE showed selectivity towards the detection of dopamine in presence of a 10-fold higher concentration of other important biomolecules. The nanocomposite film modified SPCE sensor was good stable and reproducible towards the detection of Parkinson's disease biomarker. Furthermore, the as-synthesized α-MnS@rGOS nanocomposite modified SPCE has been applied to the determination of dopamine in human serum, rat serum and pharmaceutical samples with acceptable recoveries.


Assuntos
Dopamina/análise , Eletroquímica/métodos , Grafite/química , Compostos de Manganês/química , Nanopartículas/química , Óxidos/química , Sulfetos/química , Ondas Ultrassônicas , Biomarcadores/análise , Catálise , Técnicas de Química Sintética , Eletroquímica/instrumentação , Eletrodos , Concentração de Íons de Hidrogênio , Cinética , Compostos de Manganês/síntese química , Oxirredução , Doença de Parkinson , Sulfetos/síntese química
11.
Ultrason Sonochem ; 56: 410-421, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31101279

RESUMO

To dates, the facile synthesis of inorganic-coated organic polymer composite has received greater attention in the order of research fields including advanced materials and electrochemical analysis owing to the complementary or synergistic effects. In this context, Pr2O3 and Pr2O3 coated polystyrene (Pr2O3/PS) inorganic-organic colloidal composite were prepared via ultrasound-induced radicals initiated precipitation and dispersion polymerization methods. The synthesized Pr2O3/PS composite was systematically studied by FE-SEM, TEM, EDX, FT-IR, XRD, and XPS analysis. This composite modified glassy carbon electrode (Pr2O3/PS GCE) was utilized to construct a novel electrochemical sensor for the detection assay of chemotherapy agent methotrexate (MTA). Under optimal condition, the designed sensor showed outstanding performance for MTA trace level detection over the linear concentration range of 0.01-236 µM with a detection limit of 0.8 nM for MTA. Furthermore, the prepared sensor accomplished excellent stability and relevant reproducibility, in addition to reliable practical assay in real human blood serum and urine samples. Besides, the possible MTA sensing mechanism of Pr2O3/PS GCE has been deliberated in detail. Our finding suggested that the developed Pr2O3/PS composite might be a favorable material for the fabrication of the high-performance electrochemical sensor.


Assuntos
Eletroquímica/métodos , Metotrexato/análise , Poliestirenos/química , Ondas Ultrassônicas , Eletroquímica/instrumentação , Eletrodos , Transporte de Elétrons , Radicais Livres/química , Humanos , Limite de Detecção , Metotrexato/sangue , Metotrexato/urina , Modelos Moleculares , Conformação Molecular , Oxirredução
12.
Ultrason Sonochem ; 56: 422-429, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31101280

RESUMO

The nanomaterials have received enormous attention in the catalysis applications. Particularly, we have focused on the fabrication of nanocomposite for an electrochemical sensor with improved electrocatalytic performance. Herein, a rapid and sensitive electrochemical detection of nitrite is essential for assessing the risks facing ecosystems in environment. We report a simple and robust ultrasonic-assisted synthetical route via prepared Er2O3 nanoparticles decorated reduced graphene oxide nanocomposite (Er2O3 NPs@RGO) modified electrode for nitrite detection. The composition and morphological formation were characterized by XRD, XPS, FESEM, and HRTEM. The amperometric (i-t) and cyclic voltammetry were exhibits tremendous electrocatalytic capability and superior performance toward nitrite oxidation. A sensitive and reproducible amperometric nitrite sensor was fabricated which able to detect trace concentration as 3.69 nM and excellent sensitivity (24.17 µA µM-1 cm-2). The method worked well even in cured meat and water samples and the results has indicates the reliability of the method in real-time analysis.


Assuntos
Poluentes Ambientais/análise , Érbio/química , Grafite/química , Metemoglobinemia/induzido quimicamente , Nanosferas/química , Nitritos/análise , Óxidos/química , Catálise , Técnicas de Química Sintética , Eletroquímica , Eletrodos , Poluentes Ambientais/toxicidade , Limite de Detecção , Nitritos/toxicidade , Reprodutibilidade dos Testes , Propriedades de Superfície , Ondas Ultrassônicas
13.
Ultrason Sonochem ; 56: 430-436, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31101281

RESUMO

We report a facile and ultrasound assisted sonochemical synthesis of a Tungsten disulfide nanorods decorated nitrogen-doped reduced graphene oxide based nanocomposite. The WS2 NRs/N-rGOs nanocomposite was characterized by FESEM, HRTEM, XRD, XPS and electrochemical methods and its application towards the electrochemical detection of organo-arsenic drug (coccidiostat). The WS2 NRs/N-rGOs modified SPCE was used for the electrochemical reduction of roxarsone (ROX) and it showed superior electrocatalytic performance in terms of reduction peak current and shift in overpotential when compared to those of WS2 NRs/SPCE, N-rGOs/SPCE and based SPCE. The WS2 NRs/N-rGOs modified SPCE showed an excellent sensing ability towards ROX in nitrogen saturated phosphate buffer (PB) then the other controlled modified and unmodified electrodes. The WS2 NRs/N-rGOs/SPCE displays high sensitive response towards ROX and gives wide linearity in the range of 0.1-442.6 µM ROX in neutral phosphate buffer (pH 7.0) and the sensitivity of the sensor is calculated as 14.733 µA µM-1 cm-2. The WS2 NRs/N-rGOs nanocomposite modified sensor also exhibits valuable ability of anti-interference to electroactive analytes. Furthermore, the as-prepared WS2 NRs/N-rGOs/SPCE has been applied to the determination of ROX in biological and pharmaceutical samples.


Assuntos
Antibacterianos/análise , Eletroquímica/instrumentação , Grafite/química , Limite de Detecção , Nanotubos/química , Nitrogênio/química , Roxarsona/análise , Antibacterianos/química , Catálise , Técnicas de Química Sintética , Eletrodos , Concentração de Íons de Hidrogênio , Cinética , Porosidade , Roxarsona/química
14.
Molecules ; 24(9)2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31071915

RESUMO

Exploration of efficient catalysts is a priority for the electrochemical nitrogen reduction reaction (NRR) in order to receive a high product yield rate and faradaic efficiency of NH3, under ambient conditions. In the present contribution, the binding free energy of N2, NNH, and NH2 were used as descriptors to screen the potential NRR electrocatalyst among different single or binuclear transition metal atoms on N-doped nanoporous graphene. Results showed that the binuclear Mo catalyst might exhibit the highest catalytic activity. Further free energy profiles confirmed that binuclear Mo catalysts possess the lowest potential determining step (hydrogenation of NH2* to NH3). The improved activities could be ascribed to a down-shift of the density of states for Mo atoms. This investigation could contribute to the design of a highly active NRR electrocatalyst.


Assuntos
Eletroquímica , Grafite/química , Modelos Teóricos , Molibdênio/química , Nanoporos , Nitrogênio/química , Catálise , Hidrogênio/química , Oxirredução , Termodinâmica
15.
Molecules ; 24(9)2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31071946

RESUMO

This work incorporates a variety of conjugated donor-acceptor (DA) co-monomers such as 2,6-diaminopurine (DP) into the structure of a polymeric carbon nitride (PCN) backbone using a unique nanostructure co-polymerization strategy and examines its photocatalytic activity performance in the field of photocatalytic CO2 reduction to CO and H2 under visible light irradiation. The as-synthesized samples were successfully analyzed using different characterization methods to explain their electronic and optical properties, crystal phase, microstructure, and their morphology that influenced the performance due to the interactions between the PCN and the DPco-monomer. Based on the density functional theory (DFT) calculation result, pure PCN and CNU-DP15.0 trimers (interpreted as incorporation of the co-monomer at two different positions) were extensively evaluated and exhibited remarkable structural optimization without the inclusion of any symmetry constraints (the non-modified sample derived from urea, named as CNU), and their optical and electronic properties were also manipulated to control occupation of their respective highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). Also, co-polymerization of the donor-acceptor 2,6-diamino-purine co-monomer with PCN influenced the chemical affinities, polarities, and acid-base functions of the PCN, remarkably enhancing the photocatalytic activity for the production of CO and H2 from CO2 by 15.02-fold compared than that of the parental CNU, while also improving the selectivity.


Assuntos
Dióxido de Carbono/química , Elétrons , Luz , Nitrilos/química , Polímeros/química , Adsorção , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Catálise/efeitos da radiação , Eletroquímica , Nitrogênio/química , Oxirredução , Espectroscopia Fotoeletrônica , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
16.
Chemosphere ; 229: 181-187, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31078032

RESUMO

In this study, a combined continuous flow system was designed to remove Pb and Cd from heavily contaminated mine tailing soils. 0.05 M Na2EDTA was used as a chelating agent to remove Pb and Cd from polluted soil, taken from the vicinity of Kayseri ÇINKUR, Turkey. The initial concentrations of Pb and Cd were 16381 ±â€¯643 and 34347 ±â€¯1310 mg kg-1, respectively. The electrochemical treatment process was applied to the waste washing solution, which emerged after being extracted from soil column and contained Pb and Cd. Metal ions were transformed to the metallic form by applying the electrochemical treatment process to the washing solution, containing Pb2+ and Cd2+. At the end of the leaching experiment, which was done with a 50 g soil sample in the soil column system, Pb and Cd removal efficiencies from soil were 59.72% and 58.01%, respectively. Then, the soil column solution was subjected to electrolysis through a 48 h period at 10 V. The electrochemical removal efficiency of ions, which moved from column to solution, was 84.46% for Pb and 59.21% for Cd.


Assuntos
Cádmio/química , Cádmio/isolamento & purificação , Chumbo/química , Chumbo/isolamento & purificação , Poluentes do Solo/química , Poluentes do Solo/isolamento & purificação , Solo/química , Quelantes/química , Ácido Edético/química , Eletroquímica , Recuperação e Remediação Ambiental
17.
Chemosphere ; 229: 273-283, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31078884

RESUMO

In this study, a sponge modified by multi-walled carbon nanotubes (MWNTs) was used as sheet support for the adsorption of CuO@Cu and Ag nanowires to prepare a CuO@Cu/Ag/MWNTs/sponge electrode. Similar to their use in a dielectric barrier discharge (DBD) reactor, the MWNTs changed the conductivity and water absorptivity of the modified electrode, whereas the CuO@Cu and Ag nanowires significantly enhanced the tip effect to increase discharge. The optimal ratio of the Ag:CuO@Cu nanowires was 5:3 at a total adsorbed concentration of 0.8 g L-1. Compared with CuO@Cu and Ag nanowires were separately adsorbed on the MWNTs/sponge, and the CuO@Cu/Ag/MWNTs/sponges recorded higher current response, lower discharge inception voltage, and higher removal efficiency of phenol and 2,4,5-trichlorobiphenyl (PCB29) through their degradation. The removal efficiency reached 100% within 30 min of the reaction for the degradation of phenol and 65.1% within 60 min of the reaction for the degradation of PCB29 at an input voltage of 30 V. These results show that the CuO@Cu/Ag/MWNTs/sponge structure has significant potential for use in the DBD reactor to improve the discharge efficiency of the system and reduce energy consumption, and can be further extended to other types of plasma reactors.


Assuntos
Cobre/química , Eletroquímica/instrumentação , Poluentes Ambientais/química , Poluentes Ambientais/isolamento & purificação , Nanotubos de Carbono/química , Prata/química , Adsorção , Impedância Elétrica , Eletrodos , Cinética , Nanofios/química , Água/química
18.
Environ Pollut ; 250: 906-913, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31085477

RESUMO

A novel heterogeneous Fenton-like system (Mg/Fe-O2) which could directly convert oxygen (O2) to hydrogen peroxide/hydroxyl radicals (H2O2/•OH) was developed and used to degrade 4-chlorophenol. The Mg/Fe bimetallic particles were prepared by chemical displacement process and characterized by XRD, SEM and TEM. The in situ continuous production of H2O2/•OH and the effect of the mole ratio of Mg to Fe in the Mg/Fe bimetallic particles and the operating parameters on the degradation 4-chlorophenol in Mg/Fe-O2 system were investigated in detail. It was found that the Mg/Fe bimetallic particles with the mole ratio of Mg to Fe of 32:1 had the best performance for the 4-chlorophenol degradation and the maximum cumulative concentration of H2O2, the degradation efficiency of 4-chlorophenol and the removal efficiency of TOC in Mg/Fe-O2 system were 34.5 mg/L, 100% and 91.8%, respectively, at pH 3, O2 flow rate 400 mL/min, dosage of Mg/Fe bimetallic particles 2 g/L, 4-chlorophenol initial concentration 50 mg/L and reaction time 60 min. It was revealed by radical scavenging experiments that •OH, particularly the surface-bound •OH, were the predominant reactive oxygen species in Mg/Fe-O2 system for the degradation of 4-chlorophenol. The main intermediates of 4-chlorophenol degradation were detected by high-resolution liquid chromatography equipped with time-of-flight mass spectrometry (HRLC-ToF-MS) and ion chromatography (IC). Based the results of control experiments and the electrochemical tests, the possible pathway and mechanism of 4-chlorophenol degradation in Mg/Fe-O2 system were tentatively proposed.


Assuntos
Clorofenóis/análise , Peróxido de Hidrogênio/química , Ferro/química , Magnésio/química , Oxigênio/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Catálise , Eletroquímica , Concentração de Íons de Hidrogênio , Radical Hidroxila/química , Modelos Teóricos , Oxirredução , Propriedades de Superfície
19.
Chemosphere ; 228: 744-755, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31071561

RESUMO

Electrokinetic (EK) remediation is often developed for metal decontamination but shows limitations for polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) which are nonionic and involve low aqueous solubility. This paper reports many laboratory studies devoted to the investigations of EK efficiency on the mobility and the removal of metals, PAHs and PCBs from dredged sediments, using a mixture of chelating agent and surfactants. The results showed that increasing chelating agent concentration was favorable for both metal and PAH removal. Applying a periodic voltage gradient associated to a low concentration of additives provided the best removal of Zn, Cd and Pb and also the 16 priority PAHs. The tested fresh harbor sediment was highly resistant to metals and organics mobilization and transport because of an aged contamination, a high buffering capacity, a very low hydraulic permeability and a high organic matter content. However, experiments performed on a former sediment which was deposited many years ago provided better removal results, involving low organic matter and carbonates content. The efficiency of the EK process was also assessed by measuring the acute toxicity of the EK-treated sediment on the copepod Eurytemora affinis exposed to sediment elutriates.


Assuntos
Copépodes/efeitos dos fármacos , Recuperação e Remediação Ambiental/métodos , Sedimentos Geológicos/química , Poluentes Químicos da Água/toxicidade , Animais , Quelantes/química , Eletroquímica/métodos , França , Concentração de Íons de Hidrogênio , Metais/isolamento & purificação , Bifenilos Policlorados/isolamento & purificação , Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação , Tensoativos/química , Testes de Toxicidade Aguda , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
20.
Chemphyschem ; 20(9): 1110-1125, 2019 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-30969481

RESUMO

A covalently linked BODIPY-fullerene C60 dyad (BDP-C60 ) was synthesized as a two-segment structure, which consists of a visible light-harvesting antenna attached to an energy or electron acceptor moiety. This structure was designed to improve the photodynamic action of fullerene C60 to inactivate bacteria. The absorption spectrum of BDP-C60 was found to be a superposition of the spectra of its constitutional moieties, whereas the fluorescence emission of the BODIPY unit was strongly quenched by the fullerene C60 . Spectroscopic, calculations, and redox studies indicate a competence between photoinduced energy and electron transfer. Protonating the dimethylaminophenyl substituent through addition of an acidic medium led to a substantial increase in the fluorescence emission, triplet excited state formation, and singlet molecular oxygen production. At physiological pH, photosensitized inactivation of Staphylococcus aureus mediated by 1 µM BDP-C60 exhibited a 4.5 log decrease of cell survival (>99.997 %) after 15 min irradiation. A similar result was obtained with Escherichia coli using 30 min irradiation. Moreover, proton-activated photodynamic action of BDP-C60 turned this dyad into a highly effective photosensitizer to eradicate E. coli. Therefore, BDP-C60 is an interesting photosensitizing structure in which the light-harvesting antenna effect of the BODIPY unit combined with the protonation of dimethylaminophenyl group can be used to improve the photoinactivation of bacteria.


Assuntos
Anti-Infecciosos/química , Compostos de Boro/química , Compostos de Boro/farmacologia , Fulerenos/química , Fulerenos/farmacologia , Complexos de Proteínas Captadores de Luz/química , Eletroquímica , Escherichia coli/efeitos dos fármacos , Estrutura Molecular , Fotoquimioterapia , Staphylococcus aureus/efeitos dos fármacos
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